| We live in a sensor saturated world. We can reside in smart cities while driving smart cars, live in homes with smart thermostats and many remotely connected intelligent devices. The ability to sense, measure, analyze and carry out complex functions with small sensors has undeniable impact on our culture, technology and commerce. Although electronic based sensors dominate the application market, the photonic domain for sensors has increased. Research and development in optical sensors are driven by the attractive properties, which offer significant advantages over conventional sensors. These properties include sensitivity, wide dynamic range, smaller sensing surface, higher sensing throughput, multiple signal processing, portability, low losses and electromagnetic immunity. Recently, sensor components in optical and biochemical fields have found an increasing number of applications in industry, medicine and environmental monitoring. This dissertation investigates two sensing systems in the biochemical sensing fields, with the goal of contributing more functionality and miniaturization to existing sensing devices. For potential application in drug delivery systems, porous silicon is of interest due to its unique morphological, physical and chemical properties as well as its compatibility with silicon-based microelectronics. The biocompatibility of porous silicon has opened many possibilities for innovative new sensors in nano medicine and intelligent implants. Specifically, macropores are attractive because the integration of surface modification in this material can be utilized to develop diverse novel functionalities. Thus, macroporous silicon is explored as a photodiode and host membrane for fluidic actuation. A thermo-responsive polymer/hydrogel Poly(N-isopropylacrylamide), is infiltrated within the macropores as an active fluidic control unit. In response to external stimuli, the hydrogel is reversibly switched from a water-swollen to a de-swollen state thereby acting as a microvalve and carrier medium within the pores. Thermo-responsive properties are also of key interest in the micro scale. Accurate temperature measurements are crucial for many applications where temperature differences could be used to assist in evaluation, diagnosis, product analysis or process control. Thus, a thermo-optic sensor based on resonance waveguide grating is investigated for thermal imaging applications. Resonance waveguide gratings provide an ideal configuration due to their unique properties such as high reflection efficiency and simplicity of the fabrication process. |
